Chain stacker gripper control



Nov. 5, 1963 R. REINARTZ CHAIN STACKER GRIPPER CONTROL Filed June 12,1961 2 Sheets-Sheet 1 E" .1. l5 by rum/70R.- Bobcat Rein/mt:

flttomvexs Nov. 5, 1963 R. REINARTZ CHAIN STACKER GRIPPER CONTROL 2Sheets-Sheet 2 Filed June 12, 1961 IN YEN TOR 562st Reuvaxtz ,z/gawpyaiii-Myers United States Patent 3,109,644 CHAIN STACKER GRIPPER CONTROLRobert Reinartz, Augsburg, Germany, assignor to MaschinenfabrilrAugsburg-Nurnberg A.G., Augsburg,

Germany Filed June 12, 1961, Ser. No. 116,386 Claims priority,application Germany July 22, 1960 1 Claim. (Cl. 271-68) This inventionrelates to a chain stacker for a printing press and, in particular, isdirected to a gripper chain stacker.

More particularly, the invention is directed to means for controllingthe grippers in chain stackers which have horizontally movable openingcams and which work in cooperation with a so-called following orafter-gripper.

In numerous conventional stackers, the control cams are so arranged thatthe gripper travelling with the gripper chain opens before the sheet isdropped onto the stack and passes the sheet to a pneumatic after-gripperwhich, in turn, takes the sheet and brings it with a lessened velocityto the stacking plate of the stacking table. However, the suction of theafter-gripper is not enough to grasp and hold a sheet of heavy paper orcardboard. Consequently, it has been the practice to remove and not usethe aftergrippers when handling heavy sheets or cardboard. The resulthas been that the heavy sheets or carboard strike the stacking platewithout being reduced in velocity and thereby damage the front edge ofthe sheet and produces a sloppy stack.

Attempts have been made to remedy this difiiculty by moving the openingcam surface for the gripper around the axis of the chain sprocket. Thishas not produced a sufficient delay in the time of the opening of thegripper, unless the knocking of the gripper roller against the camsurface is accepted. It has also been the practice in the stacking ofsheets in a printing press to displace the cam opening surface of thegripper in a horizontal direction. Such cam surfaces are positionedadjacent the horizontal reach of the stacker chains and used in machinesin combination with after-grippers where great emphasis is placed on compact construction. This arrangement is not serviceable because it isnecessary that the two gripper systems operate together.

The above disadvantages in the control of the grippers in a chainstacker for a printing press and in which the grippers operate inconjunction with after grippers are avoided by this invention in thatthe horizontally movable opening cam is flexibly connected to the curvedcam arm which remains substantially in the line of its curve while beingdisplaced as the gripper opening cam is moved with respect to a fixedpoint. By this construction, the delay of the opening of the gripper isgiven a greater range of time despite the fact that the after-gripper isnot in use and without running the risk that the grippers will be closedprematurely and again grasp the sheet. This invention also permits acompact construction in that the outer chain sprocket can be mountedover the stack; while at the same time, a violent impact of the heavysheets against the stacking plate is prevented.

The means by which the objects of the invention are obtained aredescribed more fully with reference to the accompanying drawings, inwhich:

FIGURE 1 is a front elevational view of the invention;

FIGURE 2 is a side view of FIGURE 1 taken in the direction o the a rowA; and

FIGURE 3 is a cross-sectional view taken on the line 3-3 of FIGURE 1.

As shown in the drawings, the gripper chain 1 carries sheet grippers 2which grasp the sheets 3. The leading edge of the sheets 3 strike thestacking plate 4 as they are deposited upon the stack. During normal useof the machine, when handling lightweight sheets, the aftergripper 5takes each sheet as it is released by the grippers 2 and moves the sheetwith reduced velocity toward stacking plate 4. In normal light sheetoperation, the opening cam 6 has the position as shown in full lines inFIG- URE l. The cam surface 7 bears upon the cam follower 7a to opengrippers 2 at this position.

When heavy paper or cardboard is being handled, the construction ismodified by extending the cam surface 7 by means of a curved cam arm 8which is pivotally joined to cam 6 by pin 9.

Cam 6 is joined to a guide 16) in the form of an elongated slot which isslidably and turnably mounted on the axle 11 of the chain sprocket and afixed stationary bearing 12. Guide Iii is movable by a lever 13connected at one end to guide 10 and at the other end to shaft 14 whichis displaceable by a gearing 14a actuated by handwheel 15. By pulling onshaft 14, the guide 10 and cam surface 7 are displaceable substantiallyparallel to the surface of the stack of sheets to a position indicatedby the dash-dot line.

A stationary bracket 16 is clamped to axle 11 and bearing 12 for holdingin a fixed position a stationary member 17 which bears against the fiatsurface 18 of the curved cam extension arm 8. The free end of arm 8 isconnected to lever 13 by a spring 19.

In operation, when the opening cam surface 7 is displaced from the fullline position shown to the dash-dot line position, the surface 18 slidesalong the stationary member 17 and is held thereagainst by means ofspring 19 so that the curved extension arm 8 remains substantially inthe line of its curve as shown by the dash-dot line. As the extensionarm has not had its cam surface displaced essentially from its originalposition, the closing of gripper 2 does not occur until the gripper haspassed beyond the leading edge of the sheet whereby the gripper cannotgrasp the sheet again once it has been released. Although the inventionhas been described for a single gripper with its opening cam andafter-gripper, it is to be understood that a plurality of grippers arearranged across the entire breadth of the machine.

Having now described the means by which the objects of the invention areobtained, I claim:

In a chain stacker for a printing press, said stacker having ahorizontally displaceable opening cam for sheet grippers operating inconjunction with after-grippers, the improvement comprising a curved camextension arm pivotally joined to said opening cam and having a surfaceforming a continuation of the surface of said opening cam, a stationarymember bearing against said arm, and means for moving said opening caminto difi 'erent positions while keeping said arm substantially in theline of its curve and bearing against said stationary member to changethe opening point of the sheet gripper while maintaining an unchangedclosing point for said sheet gripper.

References Cited in the file of this patent UNITED STATES PATENTS730,857 Annand June 16, 1903 2,813,483 Keil Nov. 19, 1957 2,969,980Claybourn Jan. 31, 1961

